Stem cells reside in specialized niches, which provide extrinsic signals that regulate their life-long self-renewal and differentiation. Adult neural stem cells continuously generate neurons in restricted parts of the brain that functionally integrate into neural circuits. These stem cells may represent an important source of endogenous cells that can be stimulated for brain repair. Defining the components of the niche that regulate adult neural stem cell behavior is essential to eventually harnessing these cells for brain repair, as well as illuminating the contribution of the niche to the decline in stem cell function that occurs with aging and disease. The subventricular zone (SVZ) is the largest germinal region in the adult brain. SVZ stem cells and their progeny reside in a specialized vascular niche. While diffusible endothelial signals are known to promote stem cell self- renewal, little is known about the contribution of other perivascular cells to the niche. We propose here to: 1) co-culture purified SVZ stem cells and their progeny with primary perivascular cells purified from the SVZ and a non-neurogenic region of the brain. In addition we will seed purified SVZ cells onto an extracellular matrix scaffold. These experiments will define the functional contribution of diffusible signals, contact-mediated signals and the extracellular matrix to adult neural stem cell proliferation and lineage progression. 2) We will perform transcriptional profiling of acutely isolated perivascular cells to identify molecular signals from the niceh. This will provide a tremendous resource for future functional in vivo and in vitro studies of niche candidates from perivascular cells. PUBLIC HEALTH RELEVANCE: This project will define the functional role of diverse aspects of the vascular niche in regulating adult neural stem cells. It will provide information about the microenvironment that supports the formation of new neurons in the adult mammalian brain and how neural stem cells are maintained throughout life. Understanding these cues will yield insight into the possibility of stimulating endogenous stem cells or activating cells elsewhere in the brain for repair.